R.I. Gen. Laws § 36-7-21

It is the intention of the general assembly by the adoption of §§ 36-7-10 — 36-7-21 that the protection afforded employees in positions covered by a retirement system, as herein defined, on the date an agreement is made applicable to service performed in those positions, or employees receiving regular payments under the retirement system at the date of the agreement, will not be impaired as a result of making the agreement so applicable or as a result of legislative enactment in anticipation of the adoption of the referendum.